popen() returns FILE* to the stdout of the command you run. So, if you want to read stderr (it looks like the command you run gives errors that goes to stderr), then
you could do redirect stderr to stdout:

FILE* lsofFile_p = popen("c:\\adb tcpip 5555 2>&1" ,"r");

Be aware that this will mix stdout and stderr. So, there's no way to differentiate output and errors, if that matters.